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TPS63070: 10.9VDC output from regulator, following reference design...?

Richard Martin
Prodigy 40 points
Part Number: TPS63070

I realize TI makes great components, but you'll have to pardon me if I think this is a bit *too* great...

I re-implemented a reference design from the WebBench; however...the output voltage from the regulator chip is 10.9 volts...! A nice, steady 1.4A as well; the chip doesn't seem to have been damaged at all, and performs very consistently...but what I really needed was 3.3VDC.

I can provide the design I created, as well as the schematic, however I promise that I re-created it faithfully. The SMT soldering was right on, too. I did another assembly of the same board, and I'm consistently having the same problem: when these chips power on, they're kicking out over 10 volts.

Any ideas?

Here's the schematic. It's right from the WebBench calculator; my component values are those shown here:

Schematic for TPS63070

I do note that the values chosen for 3.3 volts in the schematic differ from those shown in the datasheet as required to generate that voltage; are the divider settings that sensitive?

  • 0
    TI__Expert 8420 points
    Hi Martin,

    Welcome to the forum!
    Could you please post the schematic and layout of your board? Please summarize your design spec while posting the design.
    Meanwhile did you try to perform the same measurements on a TPS63070 EVM? If not I would strongly recommend to do so.
  • 0 in reply to Sabrina
    Prodigy 40 points

    It's straight out of the WebBench tool on the product page:

    Schematic for TPS63070

    The schematic is also; I started with the WebBench one:

    Board view for TPS63070

    All the component values are as specified in the schematic. These conflict, however, with the datasheet itself. I'm wondering if the voltage divider values are that sensitive..

  • 0 in reply to Richard Martin
    TI__Expert 8420 points
    This behavior is definitely not expected, It looks to me like the overvoltage protection feature is kicking in (I am guessing) described in section 8.4.8. of the DS.
    I would need YOUR layout top and bottom layer (although it is exactly the same as webbench) to help you further.

    Can you exclude that the FB is not damaged or not well soldered?
    Also could you please answer these two points:
    1. Please summarize your design spec while posting the design.
    2. Meanwhile did you try to perform the same measurements on a TPS63070 EVM? If not I would strongly recommend to do so. "

    BTW using a lower resistive divider should not be the issue here
  • 0 in reply to Sabrina
    TI__Expert 8420 points
    Hi Rich,
    As I have not heard back from you neither from private message nor on the forum, I am wondering if you were able to solve the issue?